我应该如何编译这个 C 代码？

Question

我下载了this source code (.zip)，并希望在我的 Mac (OSX 10.11.2) 上使用 XCode 版本 7.2 (7C68) 编译它。

我开始编译文件fdist.c

gcc -o fdist2 -O fdist.c -lm

但它会返回一长串警告和错误（见下文）。查看文件，我发现它确实不像我习惯的那种代码。通常，函数返回的对象类型似乎是未指定的。

README_fdist2 没有多大帮助。有关于如何编译代码的指南，但第一行有一个错字。

我应该如何编译这段代码？

---

以下是命令gcc -o fdist2 -O fdist.c -lm 返回的错误和警告

fdist2.c:42:1: warning: type specifier missing, defaults to 'int' [-Wimplicit-int]
main()
^
fdist2.c:117:3: warning: implicit declaration of function 'sim1' is invalid in C99
      [-Wimplicit-function-declaration]
                sim1(init,initot,rm,mu,freq_arr,val_arr,&noall);
                ^
fdist2.c:119:4: warning: implicit declaration of function 'my_thetacal' is invalid in C99
      [-Wimplicit-function-declaration]
                        my_thetacal(freq_arr,noall,init,Subs,&h0,&h1,&fst);
                        ^
fdist2.c:136:1: warning: type specifier missing, defaults to 'int' [-Wimplicit-int]
sim1(init,initot,rm,mu,freq_arr,val_arr,noall)
^
fdist2.c:222:3: warning: implicit declaration of function 'dfill' is invalid in C99
      [-Wimplicit-function-declaration]
                dfill();
                ^
fdist2.c:234:4: warning: implicit declaration of function 'cnode' is invalid in C99
      [-Wimplicit-function-declaration]
                        cnode(k);
                        ^
fdist2.c:237:8: warning: implicit declaration of function 'mnode' is invalid in C99
      [-Wimplicit-function-declaration]
                else mnode(k); 
                     ^
fdist2.c:252:1: warning: control may reach end of non-void function [-Wreturn-type]
}
^
fdist2.c:254:1: warning: type specifier missing, defaults to 'int' [-Wimplicit-int]
thetacal(gen,noall,sample_size,no_of_samples,het0,het1,fst)
^
fdist2.c:293:1: warning: control reaches end of non-void function [-Wreturn-type]
}
^
fdist2.c:301:1: warning: type specifier missing, defaults to 'int' [-Wimplicit-int]
dfill()
^
fdist2.c:312:1: warning: control reaches end of non-void function [-Wreturn-type]
}
^
fdist2.c:315:1: warning: type specifier missing, defaults to 'int' [-Wimplicit-int]
cnode(sp)
^
fdist2.c:349:2: error: non-void function 'cnode' should return a value [-Wreturn-type]
        return;
        ^
fdist2.c:353:1: warning: type specifier missing, defaults to 'int' [-Wimplicit-int]
mnode(sp)
^
fdist2.c:464:2: error: non-void function 'mnode' should return a value [-Wreturn-type]
        return;
        ^
fdist2.c:489:10: warning: implicit declaration of function 'poidev' is invalid in C99
      [-Wimplicit-function-declaration]
        mutno = poidev(time*mu);
                ^
fdist2.c:491:12: warning: implicit declaration of function 'addmut' is invalid in C99
      [-Wimplicit-function-declaration]
                p->dna = addmut(p->dna);
                         ^
fdist2.c:676:1: warning: type specifier missing, defaults to 'int' [-Wimplicit-int]
mom(x,n,x1,x2,x3,x4,min,max)
^
fdist2.c:707:2: error: non-void function 'mom' should return a value [-Wreturn-type]
        return;
        ^
fdist2.c:761:1: warning: type specifier missing, defaults to 'int' [-Wimplicit-int]
my_thetacal(gen,noall,sample_size,no_of_samples,het0,het1,fst)
^
18 warnings and 3 errors generated.

Answer 1

问题不在于编译器，而在于您的代码不遵循语法这一事实。 C99 要求提前声明所有变量和函数。函数和类定义应放在 .h 头文件中，然后包含在引用它们的 .c 源文件中。

即

mycode.h:

int myFunction (int a, char * s);

mycode.c

#include "mycode.h"

int main(int argc, char **argv) {
     int x = 2;
     char * str = "Hello";
     int r = myFunction(x,str);
     return r;
}

Answer 2

看起来代码不符合 C99 的隐式函数声明、默认返回 (int) 等。

修复它似乎并不难。但是，如果您不想或不能，那么您可以尝试在 implicit int return 有效的 C89/C90 中编译。这应该可以解决您收到的大部分（如果不是全部）警告。

gcc -std=c89 -o fdist2 -O fdist.c -lm